Ammonia gas is passed into water,yeilding a solution of density 0.93 g/cm3 and containing 18.6% NH3 by weight. The mass of NH3 per cc of the solution is

Applying,

Density = Mass/Volume

Hence Mass = Density x Volume

Density = 0.93g/cc

Mass of 1 cc of solution = 0.93 x 1= 0.93g

1 cc of solution =0.93g

Solution contains 18.6% ammonia by weight.

 So,1 cc of solution =18.6% of 0.93g ammonia

                               = (18.6/100) x 0.93 = 0.173g

So mass of ammonia per cc of solution is 0.173g.